import tkinter
import time
import random


class Ball():

    def __init__(self, canvas, color):
    def __init__(self, canvas, color):
        self.canvas = canvas
        self.id = canvas.create_oval(0, 0, 30, 30, fill=color)
        canvas.move(self.id, 245, 100)
        level = [-7, -5, -3, -1, 1, 3, 5, 7]
        self.x = random.choice(level)
        self.y = random.choice(level)

    def draw(self):
        self.canvas.move(self.id, self.x, self.y)
        pos = self.canvas.coords(self.id)

        if pos[3] >= 400:
            self.y = -3
        if pos[1] <= 0:
            self.y = 3
        if pos[0] <= 0:
            self.x = 3
        if pos[2] >= 500:
            self.x = -3


tk = tkinter.Tk()
tk.title("第一个自己学的小游戏")
tk.resizable(0, 0)
tk.wm_attributes('-topmost', 1)

canvas = tkinter.Canvas(tk, width=500, height=400)

canvas.pack()
tk.update()
ball = Ball(canvas, "red")
ball2 = Ball(canvas, "blue")
ball3 = Ball(canvas, "purple")

while 1:
    ball.draw()
    ball2.draw()
    ball3.draw()
    tk.update_idletasks()
    tk.update()
    time.sleep(0.01)
